1. Field of the Invention
The present invention relates to a process for manufacturing soybean proteins and, more particularly, to a process for manufacturing soybean proteins particularly suitable as edible proteins.
2. Description of the Prior Art
Heretofore, processes have been known for manufacturing soybean proteins, for producing soybean protein concentrates by removing saccharides by washing defatted soybean with an acid or by extracting defatted soybean with water, and for manufacturing isolated soybean proteins by a combination of the acid washing and the water extraction. The soybean proteins produced by these processes, however, all smell like raw soybean and have an unfavorable color tone so that they are not suitable as edible proteins.
When defatted soybean is washed with an organic solvent such as alcohol, soybean protein concentrates which have excellent flavor and color tone are obtained. Accordingly, if proteins alone can be extracted and separated from such soybean protein concentrates, soybean proteins which have desirable flavor and color tone and a high solubility would be produced. In order to sufficiently remove saccharides, pigment ingredients and odor causing ingredients, however, washing with hydrated alcohol containing some water is required. Washing with such an organic solvent may denature the soybean proteins and render them so insoluble that further extraction and separation become impossible. Proteins which are only slightly soluble in water may provide only limited utilization as food. Furthermore, water-insoluble fibrous portions derived from soybean may remain intact in proteinous products, giving them a rough texture, so that they are not desired as edible proteins.